U.S. patent number 5,476,562 [Application Number 08/348,761] was granted by the patent office on 1995-12-19 for large diameter electrically fusible pipe methods.
This patent grant is currently assigned to Central Plastics Company. Invention is credited to James A. Inhofe, Jr..
United States Patent |
5,476,562 |
Inhofe, Jr. |
December 19, 1995 |
Large diameter electrically fusible pipe methods
Abstract
Methods of producing electrically fusable sleeve connectors for
connecting large diameter thermoplastic pipe sections and the
sleeve connectors produced by such methods are provided. Methods of
sealingly connecting adjacent ends of a pair of large diameter
thermoplastic pipe sections by electric fusion are also provided.
The methods of producing electrically fusable thermoplastic sleeve
connectors broadly include the steps of winding a tape of molten
thermoplastic material onto a large diameter core drum whereby
adjacent windings are fused and upon being cooled a solid sleeve is
formed, embedding an electric resistance heating wire in a surface
of the sleeve while the thermoplastic material is still in the
molten state and removing the sleeve after cooling with electric
resistance heating wire embedded therein from the core drum.
Inventors: |
Inhofe, Jr.; James A. (Sapulpa,
OK) |
Assignee: |
Central Plastics Company
(Shawnee, OK)
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Family
ID: |
26673473 |
Appl.
No.: |
08/348,761 |
Filed: |
December 2, 1994 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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96453 |
Jul 26, 1993 |
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4789 |
Jan 14, 1993 |
5252157 |
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866297 |
Apr 13, 1992 |
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594047 |
Nov 1, 1990 |
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345455 |
May 1, 1989 |
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Current U.S.
Class: |
156/156; 156/171;
156/244.13; 138/174; 156/172; 156/173; 156/195; 156/308.2; 138/153;
138/144; 156/274.2 |
Current CPC
Class: |
B29C
33/505 (20130101); B29C 65/342 (20130101); B29C
66/1122 (20130101); B29C 66/5221 (20130101); B29C
66/612 (20130101); B29C 66/636 (20130101); B29D
23/005 (20130101); F16L 47/03 (20130101); H05B
3/58 (20130101); B29C 66/5229 (20130101); B29C
66/1142 (20130101); B29C 48/09 (20190201); B29C
65/3468 (20130101); B29C 65/3476 (20130101); B29C
53/56 (20130101); B29C 66/71 (20130101); Y10T
156/1026 (20150115); B29C 48/00 (20190201); Y10T
156/1043 (20150115); Y10T 156/1002 (20150115); B29C
66/71 (20130101); B29K 2023/00 (20130101) |
Current International
Class: |
B29C
33/48 (20060101); B29C 33/50 (20060101); B29C
65/00 (20060101); B29C 65/34 (20060101); B29D
23/00 (20060101); H05B 3/54 (20060101); H05B
3/58 (20060101); B29C 53/56 (20060101); B29C
53/00 (20060101); B29C 47/00 (20060101); B32B
031/00 () |
Field of
Search: |
;156/156,171,172,173,195,244.13,274.2,308.2 ;138/144,153,174 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0217080 |
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Nov 1956 |
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AU |
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1071433 |
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Dec 1959 |
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DE |
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161116 |
|
0000 |
|
JP |
|
1121850 |
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Jul 1968 |
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GB |
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Primary Examiner: Barry; Chester T.
Attorney, Agent or Firm: Dougherty, Hessin, Beavers &
Gilbert
Parent Case Text
This is a continuation of application Ser. No. 08/096,453 filed on
Jul. 26, 1993, now abandoned, which is a continuation of
application Ser. No. 08/004,789 filed on Jan. 14, 1993, now U.S.
Pat. No. 5,252,157, which is a continuation of application Ser. No.
07/866,297 filed on Apr. 13, 1992, now abandoned, which is a
continuation of application Ser. No. 07/594,047 filed on Nov. 1,
1990, now abandoned, which is a division of application Ser. No.
07/345,455, filed on May 1, 1989, now abandoned.
Claims
What is claimed is:
1. A method of producing an electrically fusible solid
thermoplastic sleeve connector for longitudinally connecting large
diameter thermoplastic pipe sections comprising the steps of:
(a) extruding a tape of molten thermoplastic material;
(b) winding said tape of molten thermoplastic material onto a large
diameter core drum having a winding surface of about 24 inches in
diameter or greater to form a sleeve whereby adjacent windings in
said sleeve are fused and upon being cooled a solid large diameter
pipe connector is formed, said core drum having an inflated bladder
attached thereto which forms said winding surface thereof;
(c) embedding at least one electric resistance heating wire within
and adjacent a surface of said sleeve while said thermoplastic
material is in the molten state;
(d) allowing said thermoplastic material to cool whereby a solid
large diameter sleeve pipe connector is formed; and
(e) removing said cooled solid large diameter sleeve pipe connector
with said electrical resistance heating wire embedded therein from
said core drum.
2. The method of claim 1 wherein said electric resistance heating
wire is placed on said core drum prior to winding said tape of
thermoplastic material thereon whereby said wire is embedded in the
internal surface of said sleeve.
3. The method of claim 1 wherein said electric resistance heating
wire is wound onto the external surface of said sleeve while said
thermoplastic material is in the molten state whereby said wire is
embedded in the external surface thereof.
4. The method of claim 1 which is further characterized to include
the step of deflating said bladder prior to removing said sleeve
from said core drum in accordance with step (e).
5. The method of claim 1 wherein said thermoplastic material is
comprised of a polyolefin resin.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to large diameter electrically
fusible thermoplastic pipe connectors, methods of producing such
connectors and methods of sealingly connecting adjacent ends of
large diameter thermoplastic pipe sections by electric fusion.
2. Description of the Prior Art
Various extrusion and molding methods have been developed and used
heretofore for producing large diameter pipe from thermoplastic
materials. A number of such methods include the steps of wrapping
extruded plastic in the molten state about a form or mandrel so
that adjoining edges and surfaces of the tape are fused. Upon
removing the wrapped thermoplastic material when cooled from the
mandrel a solid tubular pipe or product is formed.
Large diameter pipe formed of thermoplastic material is finding
increased acceptance in applications such as large water and sewer
lines due to the excellent deterioration resistance, light weight
and substantially unlimited service of such pipe. However, because
of the large diameter of the pipe, sealingly connecting the ends of
adjacent pipe sections has heretofore been burdensome and
expensive.
By the present invention, electrically fusible thermoplastic sleeve
connectors for connecting large diameter thermoplastic pipe
sections, methods of producing such electrically fusible sleeve
connectors and methods of sealingly connecting adjacent ends of
large diameter thermoplastic pipe sections utilizing electric heat
fusion are provided. The electrically fusible thermoplastic sleeve
connectors and methods of the present invention make the use of
large diameter thermoplastic pipe sections more economical and
practical.
SUMMARY OF THE INVENTION
In one aspect of the present invention, methods of producing
electrically fusible thermoplastic sleeve connectors for connecting
the ends of large diameter thermoplastic pipe sections are
provided. The methods basically comprise the steps of winding a
tape of molten thermoplastic material onto a core drum whereby
adjacent windings are fused and when cooled a solid sleeve is
formed, embedding at least one electric resistance heating wire in
a surface of the sleeve while the thermoplastic material is in the
molten state, and after cooling removing the sleeve with electric
resistance heating wire embedded therein from the core drum.
The electric resistance heating wire can be placed on the core drum
prior to winding the tape of thermoplastic material thereon whereby
the wire is embedded in the internal surface of the resulting
sleeve. Alternatively, the electric resistance heating wire can be
wound onto the external surface of the sleeve while the
thermoplastic material thereof is in the molten state so that the
wire is embedded in the external surface of the sleeve.
In another aspect of the present invention, electrically fusible
large diameter plastic sleeve connectors produced in accordance
with the above-described method are provided. The connectors can be
utilized to sealingly connect adjacent ends of large diameter
thermoplastic pipe sections either on the outsides of the pipe
sections or on the insides of the pipe sections.
Finally, in yet another aspect of the present invention, methods of
sealingly connecting adjacent ends of a pair of large diameter
thermoplastic pipe sections by electric fusion are provided. The
methods basically comprise the first step of moving a large
diameter thermoplastic sleeve connector over the end and a distance
down the length of a first of the pipe sections. The second pipe
section is then placed in alignment with the first pipe section
whereby an end of the second pipe section is positioned adjacent an
end of the first pipe section. An electric resistance heating wire
is wrapped around the external surfaces of the pipe sections next
to the adjacent ends thereof, and the sleeve connector is moved to
a position over the adjacent ends of the pipe sections and over the
electric resistance heating wire. Finally, an electric current is
applied to the electric resistance heating wire for a period of
time such that the thermoplastic materials making up adjacent
portions of the sleeve and pipe sections are sealingly fused
together.
In a preferred embodiment, the large diameter sleeve connector
includes a longitudinal split formed therein whereby the internal
diameter of the sleeve can be enlarged by spreading the faces of
the split apart. Also, the faces of the split can be shaved to
reduce the internal diameter of the sleeve connector if required by
variations in the external diameter of the pipe sections to be
connected. The faces of the split can be fused together prior to
electrically fusing the sleeve to the pipe sections utilizing
either heating iron butt fusion techniques or electrofusion
techniques. When the faces of the split are fused together
electrically, such fusion can be carried out before or
simultaneously with the fusion of the sleeve to the pipe
sections.
It is, therefore, an object of the present invention to provide
large diameter electrically fusible pipe connectors and methods of
producing such connectors.
A further object of the present invention is the provision of
methods of sealingly connecting adjacent ends of large diameter
thermoplastic pipe sections by electric fusion.
Other and further objects, features and advantages of the present
invention will be readily apparent to those skilled in the art upon
a reading of the description of preferred embodiments which follows
when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic illustration of apparatus for carrying out
the method of producing electrically fusible thermoplastic sleeve
connectors of the present invention.
FIG. 2 is a schematic illustration of the apparatus of FIG. 1 in a
different mode of operation.
FIG. 3 is a cross-sectional view taken along line 3--3 of FIG.
2.
FIG. 4 is a side elevational view, partially in cross section,
illustrating a pair of pipe sections with a sleeve connector of the
present invention positined thereon.
FIG. 5 is a side elevational view, partially in cross section, of a
pair of pipe sections having an alternate form of sleeve connector
of the present invention positioned thereon.
FIG. 6 is a side elevational view of a large diameter thermoplastic
pipe section having a split sleeve connector disposed thereon.
FIG. 7 is a side elevational view illustrating the pipe section of
FIG. 6 after a second pipe section has been aligned therewith and
an electric resistance heating wire has been wound on the end
portions of the pipe sections.
FIG. 8 illustrates the pipe sections of FIG. 7 during the movement
of the split sleeve connector towards a position over the adjacent
ends of the pipe sections.
FIG. 9 illustrates the pipe sections of FIG. 8 after the sleeve
connector has been positioned over the adjacent ends of the pipe
sections and the faces of the split in the connector have been
fused.
DESCRIPTION OF PREFERRED EMBODIMENTS
In one aspect of the present invention, methods of producing
electrically fusible thermoplastic sleeve connectors for sealingly
connecting adjacent ends of large diameter thermoplastic pipe
sections are provided. In accordance with the methods, and
referring to FIG. 1 of the drawings, a tape of molten thermoplastic
material 10 extruded from an extruder 12 is wound onto a large
diameter core drum 14. The extrusion of the continuous tape 10 of
molten thermoplastic material by means of the extruder apparatus 12
is well known in the art. The thermoplastic material utilized can
be any of a variety of heretofore used thermoplastic compositions
which melt and are moldable at relatively low temperatures, and
when cooled, form high strength, corrosion resistant durable
objects. Such thermoplastic compositions are comprised of organic
polymer resins and various additives such as plasticizers, mold
release agents, corrosion inhibitors, etc. Thermoplastic materials
which are particularly suitable for use in accordance with the
present invention are those containing polyolefin resins such as
polyethylene and polybutylene.
As illustrated in FIG. 1, a continuous length of the tape 10 of
molten thermoplastic material is wound onto the large diameter core
drum 14 whereby adjacent edges of each winding are fused. In the
embodiment illustrated, a continuous length of an electric
resistance heating wire 16 is placed on the drum 14 prior to
winding the molten thermoplastic material thereon. While various
kinds of wire can be utilized, an example of a typical electric
resistance heating wire 16 is copper wire having a diameter in the
range of from about 0.4 mm to about 3 mm. The opposite ends 18 and
20 of the wire 16 extend outwardly and are passed between adjacent
thermoplastic material windings so that they extend to the exterior
of the sleeve 22 formed on the drum 14 as illustrated in FIG.
2.
As will be understood, one or multiple layers of the molten
thermoplastic material can be wound onto the core drum 14 whereby
adjacent edges and other contacting surfaces of the windings are
fused. Upon completion of the winding process as illustrated in
FIG. 2, the tape is severed and the formed sleeve connector 22 is
allowed to cool on the core drum 14.
The winding of the molten thermoplastic material onto the drum 14
causes the heating wire to be embedded in the thermoplastic
material adjacent the interior surface of the sleeve 22. When it is
desirable to produce a sleeve connector having electric resistance
heating wire embedded therein adjacent the external surface
thereof, the tape 10 of molten thermoplastic material is first
wound onto the core drum 14 followed by the winding of heating wire
on the external surface of the formed sleeve 22 whereby the heating
wire is embedded therein. As will be understood, the core drum 14
can be heated if required to maintain the thermoplastic material in
the molten state while the electric resistance heating wire is
wound thereon and/or to facilitate the fusing of multiple tape
layers. The terms "embedded" or "embedding" are used herein to mean
the placement of an electric resistance heating wire within and
adjacent a surface of a sleeve connector.
Referring now to FIG. 3, the large diameter core drum 14 with the
formed thermoplastic sleeve connector 22 thereon is illustrated in
detail. While the drum 14 can take any convenient form it must be
subject to disassembly to the extent required for the formed sleeve
connector 22 to be removed therefrom. In the form illustrated in
FIG. 3, the drum 14 is comprised of two opposing cylindrical parts
24 and 26 which can be assembled to form the cylindrical core drum
14 as shown. Disposed around the exterior surface of the core drum
14 is an inflated bladder 28 formed of flexible material. The
exterior surface of the bladder 28 forms the winding surface on
which the sleeve 22 with electric resistance heating wire embedded
therein is formed. An inflating or deflating nozzle portion 30 of
the bladder 28 extends through an opening 32 in the part 24 of the
core drum 14. A valve 34 is connected to the nozzle 30 within the
interior of the core drum 14.
In removing the formed sleeve connector 22 from the core drum 14,
the bladder 28 is deflated by opening the valve 34. Once the
bladder 28 has been deflated to the required extent, the part 26 of
the core drum 14 is withdrawn from within the bladder 28 and
removed. The formed and cooled sleeve connector 22 is then also
removed from the bladder 28.
Referring now to FIG. 4, the electrically fusible sleeve connector
22 is illustrated positioned over the adjacent aligned ends of a
pair of thermoplastic pipe sections 36 and 38. The electric
resistance wire 16 is embedded in the sleeve connector 22 adjacent
the internal surface thereof, and therefore the heating wire 16
lies adjacent the external surfaces of the end portions of the pipe
sections 36 and 38. In order to sealingly connect the pipe sections
36 and 38 to the sleeve connector 22 an electric current is applied
to the heating wire 16 by way of the ends 18 and 20 for a period of
time such that the thermoplastic materials making up adjacent
portions of the sleeve connector 22 and pipe sections 36 and 38 are
sealingly fused together.
Referring now to FIG. 5, a pair of large diameter thermoplastic
pipe sections 40 and 42 are illustrated positioned end-to-end. A
sleeve connector 44 is disposed within the adjacent end portions of
the pipe sections 40 and 42. The sleeve connector 44 includes
electric resistance-heating wire 46 embedded within the exterior
surface thereof, and the opposite ends 48 and 50 of the wire 46
extend from the sleeve connector 44 between the ends of the pipe
sections 40 and 42 to the exterior of the pipe sections. The sleeve
connector 44 is fused to the pipe sections 40 and 42 by applying an
electric current to the electric resistance heating wire by way of
the ends 48 and 50.
In another aspect of the present invention, methods of sealingly
connecting adjacent ends of a pair of large diameter thermoplastic
pipe sections by electric fusion are provided. The methods utilize
a thermoplastic sleeve connector which does not include electric
resistance heating wire embedded therein. Instead, the heating wire
is wound on the external surfaces of the end portions of the pipe
sections to be connected.
Referring to FIGS. 6-9, and particularly FIG. 6 thermoplastic
sleeve connector 52 is placed over the end of a pipe section 54 and
moved a distance in the direction of the arrow 56 down the length
of the pipe section 54. As shown in FIG. 7, a second pipe section
58 is then positioned with an end thereof adjacent the end of the
pipe section 54, and an electric resistance heating wire 60 is
wound onto the end portions of the pipe sections 54 and 58 next to
the adjacent ends thereof. Opposite end portions 62 and 64 of the
heating wire 60 extend outwardly from the external surfaces of the
pipe sections 54 and 58, respectively.
As shown in FIGS. 6 and 7, the sleeve connector 52 includes a
longitudinal split 66 formed therein whereby the internal diameter
of the connector 52 can be made larger by spreading the faces of
the split 66 apart. This ability to enlarge the internal size of
the sleeve connector 52 facilitates its movement on the pipe
sections 54 and 58.
Referring now to FIG. 8, the sleeve connector 52 is next moved in
the direction of the arrow 68 to the position illustrated in FIG.
9, i.e., to a position whereby the sleeve connector 52 is over the
adjacent ends of the pipe sections 54 and 58 and over the
electrical resistance heating wire 60 wound on the pipe sections.
Once properly positioned, the end portions 62 and 64 of the heating
wire 60 are passed through the split 66 of the connector 52 and the
faces of the split 66 are moved together and fused using known butt
fusing or electrofusion apparatus and techniques. In order to
sealingly connect the adjacent ends of the pipe sections 54 and 58
to the sleeve connector 52, an electric current is applied to the
heating wire 60 by way of the end portions 62 and 64 thereof for a
period of time sufficient for the thermoplastic materials making up
adjacent portions of the sleeve connector 52 and pipe sections 54
and 58 to be fused together.
In order to further illustrate the methods and Sleeve connectors of
the present invention, the following examples are given.
EXAMPLE 1
A continuous molten tape of polyethylene thermoplastic material is
extruded having cross-sectional dimensions of about 125 mm.times.3
mm. The molten tape is wound on a core drum having an external
inflatable bladder winding surface of about 24 inches in diameter
and having about 100 feet of about 2 mm diameter electric
resistance heating wire wound thereon. The tape of thermoplastic
material in the molten state is wound on the core drum in multiple
layers whereby adjacent edges of the tape are fused, and a sleeve
connector having an internal diameter of about 24 inches, an
external diameter of about 26 inches, and about 14 windings of
electric heating resistance wire embedded therein adjacent the
internal surface thereof is formed. After cooling whereby the
sleeve connector is solidified, the connector is removed from the
core drum.
EXAMPLE 2
A connector produced as described above is used to sealingly
connect adjacent ends of a pair of 24-inch O.D. thermoplastic pipe
sections formed of polyethylene thermoplastic material. Once
positioned over the adjacent end portions of the pipe sections, an
electric current is applied to the heating wire in a known manner
whereby the thermoplastic materials making up adjacent portions of
the sleeve connector and pipe sections are sealingly fused
together.
EXAMPLE 3
Thermoplastic pipe sections having external diameters of about 24
inches are sealingly connected by electric fusion as follows. A
thermoplastic sleeve connector of about 24 inches inside diameter,
about 26 inches outside diameter and a length of about 2 feet is
placed over the end of one of the pipe sections and moved a
distance down the length thereof. The sleeve connector includes a
longitudinal split formed therein. The second pipe section is
placed in alignment with the first pipe section whereby an end of
the first pipe section is positioned adjacent an end of the second
pipe section. A 100-foot length of about 2 mm diameter copper
electric resistance heating wire is wrapped around the external
surfaces of the pipe sections next to the adjacent ends thereof.
The sleeve connector is moved over the adjacent ends of the pipe
sections and over the heating wire wrapped thereon. The opposite
end portions of the heating wire are passed through the split in
the connector. The faces of the split in the connector are fused
together using heating irons and an electric current is applied to
the resistance heating wire by way of the ends thereof in a Known
manner whereby the thermoplastic materials making up adjacent
portions of the sleeve connector and pipe sections are sealingly
fused together.
Thus, the present invention is well adapted to carry out the
objects and attain the ends and advantages mentioned as well as
those inherent therein. While presently preferred embodiments of
the invention have been described for purposes of disclosure,
numerous changes in the arrangements of steps and components can be
made by those skilled in the art, which changes are encompassed
within the spirit of this invention as defined by the appended
claims.
* * * * *